Perineural fibrosis with axonal degeneration and vascular proliferation of the common digital nerve of the second or third intermetatarsal space are often referred to as a Morton's neuroma. It is believed that fibrosis along with degeneration of the nerve occurs as a result of mechanical irritation or entrapment between the adjacent metatarsal heads. Pain, tingling and numbness are the most common symptoms. Pain can progress to lifestyle limiting.
Referring now to FIG. 1, Morton's neuroma (also known as Morton neuroma, Morton's metatarsalgia, Morton's neuralgia, plantar neuroma, intermetatarsal neuroma, and interdigital neuroma) is a benign neuroma of an intermetatarsal plantar nerve, most commonly of the second and third intermetatarsal spaces (between 2nd-3rd and 3rd-4th metatarsal heads).
Prior art treatment has included shoe modification, use of orthotic devices, corticosterioid injections, alcohol sclerosing injections, and surgical neurectomy.
A fibroma is a non-cancerous, i.e., benign, fibrous tissue tumor or growth, that can occur anywhere in the body. For example, on the plantar, or the bottom surface of the foot, the fibromas are called plantar fibromas. Unlike plantar warts, which grow on the skin, plantar fibromas grow within the plantar fascia, which is a thickened, fibrous sheet of connective tissue that originates from the plantar aspect of medial tubercle of the calcaneus and extends to the plantar plates of the metatarsophalangeal joints with a function of absorbing shock for the foot during ambulation. The plantar fascia is one of the most important ligamentous bands that maintain the longitudinal arch of the foot.
The etiology of plantar fibromas have not been clearly identified, but it is more than likely multifactorial. The typical etiology is repetitive stress overload to the origin of the plantar fascia, together with other causes, such as weight gain, excessive pronation, occupation-related activity, anatomical variations, altered biomechanics (i.e., gait abnormalities), overexertion, and inadequate foot wear.
Plantar fibromas can develop in one or both feet and the common growth is usually a solitary nodule, though multiple nodules are possible in the same foot. The mid-arch region of the foot is the most common location for planter fibromas to develop. However, plantar fibromas can appear anywhere along the underside of the foot. They can occur in people of any age and gender and will not resolve on their own or become smaller without proper treatment.
Prior art treatment can be divided into conservative and surgical measures. Conservative and prior art non-surgical measures can alleviate the pain of a plantar fibroma, but they will not reduce the mass or prevent the progression of the plantar fibroma. These measures typically include steroid injections, orthotic devices (i.e., orthopedic shoe insoles), anti-inflammatory drugs, and physical therapy. Operative measures are needed when the above measures fail to improve symptoms of the plantar fibroma. However, surgical removal of the plantar fibroma requires outpatient care and may result in a flattening of the arch or development of hammertoes. Recurrence of the plantar fibroma occurs even after surgical measures.